Process for preparing high purity dihydroisophorone

ABSTRACT

IN THE HYDROGENATION OF ISOPHORONE TO DIHYDROISOPHORONE, MAINTAINING THE REACTION ZONE AT ELEVATED PRESSURES UNDER MILD TEMPERATURE CONDITIONS SIGNIFICANTLY IMPROVES THE SELECTIVITY TO DIHYDROISOPHORONE AT HIGH CONVERSION LEVELS. ISOPHORONE IS CONTACTED WITH HDYROGEN IN THE PRESENCE OF A HYDROGENATION CATALYST IN A HYDROGENATION ZONE WHEREIN THE HYDROGEN PRESSURE IN SAID ZONE IS MAINTAINED BETWEEN ABOUT 10-200 P.S.I.G. AND THE TEMPERATURE IN SAID ZONE RANGES FROM ABOUT 25* TO LESS THAN 175*.C THE HYDROGENATION REACTION PRODUCT RECOVERED FROM THE REACTION ZONE IS DISTILLED TO OBTAIN SUBSTANTIALLY PURE DIHYDROISOPHORONE. IN A PREFERRED EMBODIMENT, THE HYDROGENATION REACTION PRODUCT IS DISTILLED IN A FIRST ZONE TO SEPARATE THE DISTILLATE COMPRISING DIHYDROISOPHORONE AND B-ISOPHRONE FROM THE RESIDUE COMPRISING A-ISOPHORONE. THE DISTILLATE WITHDRAWN FROM THE FIRST ZONE IS THEN PASSED TO A SECOND ZONE WHEREIN SAID DISTILLATE IS HEATED AT A TEMPERATURE SUFFICIENT TO SUBSTANTIALLY ISOMERIZE B-ISOPHORONE TO A-ISOPHORONE WITHOUT CAUSING PYROLYSIS OF THE REMAINDER OF SAID DISTILLATE. THE EFFLUENT FROM SAID SECOND ZONE IS THEN PASSED TO A THIRD ZONE TO SEPARATE THE DISTILLATE COMPRISING DIHYDROISOPHORONE FROM THE RESIDUE COMPRISING A-ISOPHORONE.

EFENSTVE UBLTGATIUN UNITED STATES PATENT OFFICE Published at the requestof the applicant or owner in accordance with the Notice of Dec. 16,1969, 869 O.G. 687. The abstracts of Defensive Publication applicationsare identified by distinctly numbered series and are arrangedchronologically. The heading of each abstract indicates the number ofpages of specification, including claims and sheets of drawingscontained in the application as originally filed. The files of theseapplications are available to the public for inspection and reproductionmay be purchased for 30 cents a sheet.

Defensive Publication applications have not been examined as to themerits of alleged invention. The Patent Office makes no assertion as tothe novelty of the disclosed subject matter.

PUBLISHED NOVEMBER 30, 1971 T892,018 PROCESS FOR PREPARING HIGH PURITYDIHYDROISOPHORONE William E. Wellman, 24 Cambridge Road, Edison, NJ.

08817; Paul E. Burton, 761 Austin St., Westfield, NJ.

07090; and William D. Diana, 1001 Shadow Oak Lane,

Somerville, NJ. 08876 Filed Sept. 10, 1968, Ser. No. 758,839 Int. Cl.C07c 45/00, 49/30 US. Cl. 260-586 R 1 Sheet Drawing. 28 PagesSpecification In the hydrogenation of isophorone to dihydroisophorone,maintaining the reaction zone at elevated pressures under mildtemperature conditions significantly improves the selectivity todihydroisophorone at high conversion levels. Isophorone is contactedwith hydrogen in the presence of a hydrogenation catalyst in ahydrogenation zone wherein the hydrogen pressure in said zone ismaintained between about 10 to 200 p.s.i.g. and the temperature in saidzone ranges from about 25 to less than 175 C. The hydrogenation reactionproduct recovered from the reaction zone is distilled to obtainsubstantially pure dihydroisophorone. In a preferred embodiment, thehydrogenation reaction product is distilled in a first zone to separatethe distillate comprising dihydroisophorone and B-isophorone from theresidue comprising a-iSO- phorone. The distillate withdrawn from thefirst zone is then passed to a second zone wherein said distillate isheated at a temperature sufi'lcient to substantially isomerizeB-isophorone to a-isophorone without causing pyrolysis of the remainderof said distillate. The eifiuent from said second zone is then passed toa third zone to separate the distillate comprising dihydroisophoronefrom the residue comprising a-isophorone.

av. 30,, 1971 w. E. WELLMAN ETAL 1 PROCESS FOR PREPARING HIGH PURITYDIHYDROISOPHORONE Filed Sept. 10. 1968 I I HHMOJ.

NOLLVT'ILLSIG AHorney

